Linda Mendoza says her life began changing for the better the day she was robbed at gunpoint.

In 2010, Mendoza had just opened her beauty salon on International Boulevard in East Oakland when three men walked through the door, pointed a gun at her pregnant belly and demanded cash.

The holdup left her shaken. Mendoza, an undocumented Mexican immigrant who had lived in Oakland since she was 4, packed up her salon and moved away from her childhood neighborhood. But the 22-year-old said the crime also produced a gift: Last year, she was granted temporary residency in the United States.

Mendoza applied for a U visa through an immigration program that gives victims of serious crimes temporary residency status in exchange for cooperation in catching the perpetrators.

Nationwide, immigration authorities have reported a substantial increase in U visa applications. In the Bay Area, the Oakland Police Department has seen the number of visas for immigrant victims skyrocket.

In 2007, Oakland police processed three applications. In 2011, they processed 502.

More cooperation

Immigration rights advocates applaud the help for victims, but authorities say the main success of the program is in breaking down barriers between police and immigrants who often are hesitant to contact them.

Despite a shrinking staff, Oakland police officials said they have expanded the program because they believe it builds trust.

"We offer U visas as a way to assure them that they don't have to have any fear of us trying to get them deported," said Capt. Johnny Davis, who oversaw the program until July. "We want to help them solve their crimes."

The U visa requires police or prosecutors to sign a form confirming the applicant suffered a crime and cooperated in the investigation. Only certain crimes qualify - mostly violent felonies and domestic violence. In Oakland, police have used the visa in some cases as leverage to persuade victims to cooperate during an investigation.

Once a visa is awarded, the victim receives a work permit and is allowed to apply for permanent residency after four years.

Some are selective

While Oakland approves almost all the applications it receives, other departments are more selective.

San Jose police direct applicants to the Santa Clara County district attorney.

Lt. Dennis Kahane, who reviews U visa applications for the Contra Costa County Sheriff's Office, said he has not found that the visas offer a sufficient incentive for undocumented immigrants to help police. He said many applications come from immigrants with older cases who are in the midst of deportation proceedings and are using the visas as a last-ditch effort to obtain citizenship.

Some attorneys, Kahane said, ask him to approve applicants with nonqualifying crimes by arguing that the victim's suffering was worse than it appeared on paper.

"The law is somewhat ambiguous," he said. "Most of the guidance on U visa law interpretation comes from U visa advocates. And they, of course, want it interpreted in the most broad manner possible."

Running out

There are not enough visas to go around. This year, the House rejected a measure that would have increased the annual allowance from 10,000 to 15,000. In the fiscal year that ended Sept. 30, the Department of Homeland Security ran out of U visas in August.

Davis, the Oakland police captain who previously oversaw the program, said its success is in the progress he sees in the community, such as more people calling the police for help.

In Mendoza's case, the three suspects had robbed several other stores in the neighborhood, but no one had ever called the police. The fear extended to the court system. For weeks, Mendoza begged a woman from a nearby sandwich shop to testify in her case against the robbers.

"She didn't speak English at all. She was terrified," Mendoza recalled. "I myself speak English, so I kind of understand. People who don't speak English, they just have no idea what they're getting into."

Chance conversation

Months later, Mendoza's grandmother happened to meet someone on a bus who told her about the U visa. Mendoza reached out to a local nonprofit and eventually found Susan Bowyer, directing attorney of the Immigration Center for Women and Children's San Francisco office, who helped Oakland establish its policy.

In the end, the three suspects in Mendoza's case were arrested, she testified and they were convicted.

Mendoza is now pursuing an acting career in Los Angeles and plans to start taking college classes in January.

"I've never, ever experienced something like that before," she said, recalling the holdup. "When they left, I was terrified. Now I tell people, 'You need to make a police report. You have to do it, because otherwise these guys are going to come back on the street.' "